valid

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

adj. Well grounded; just: a valid objection.

adj. Producing the desired results; efficacious: valid methods.

adj. Having legal force; effective or binding: a valid title.

adj. Logic Containing premises from which the conclusion may logically be derived: a valid argument.

adj. Logic Correctly inferred or deduced from a premise: a valid conclusion.

adj. Archaic Of sound health; robust.

from Wiktionary, Creative Commons Attribution/Share-Alike License

adj. Well grounded or justifiable, pertinent.

adj. Acceptable, proper or correct.

adj. Related to the current topic, or presented within context, relevant.

adj. A formula or system that evaluates to true regardless of the input values.

adj. An argument whose conclusion is always true whenever its premises are true.

from the GNU version of the Collaborative International Dictionary of English

adj. Strong; powerful; efficient.

adj. Having sufficient strength or force; founded in truth; capable of being justified, defended, or supported; not weak or defective; sound; good; efficacious.

adj. Having legal strength or force; executed with the proper formalities; incapable of being rightfully overthrown or set aside.

from The Century Dictionary and Cyclopedia

Strong: powerful; efficient.

Sufficiently supported by fact; well-grounded; sound; just; good: capable of being justified or defended; not weak or defective: as, a valid reason; a valid objection.

Good or sufficient in point of law; efficacious; executed with the proper formalities; incapable of being rightfully overthrown or set aside; sustainable and effective in law, as distinguished from that which exists or took place in fact or appearance, but has not the requisites to entitle it to be. recognized and enforced by law: as, a, valid deed; a valid covenant; a valid instrument of any kind; a valid claim or title; a valid marriage; a valid ordination.—4. In zoology and hot., having sufficient classificatory strength or force; scientifically founded or well-grounded; securely established: as, a valid family, genus, or species; & valid classification.

In logic, having, as an argument, that degree of formal strength and truth that it professes to have.

In chem., having valence: chiefly used in composition, as in univalid for univalent, etc.